Tape measure with epicyclic gear drive for tape retraction

ABSTRACT

A tool, such as a tape measure, including a spring-based retraction system is shown. The retraction system utilizes an epicyclic gear train coupled between the tape blade winding reel and a rotating arbor or axle within the tape measure. A spiral spring has an outer end coupled to the reel and an inner end coupled to the axle. The gear train may be a reduction gear train such that the axle rotates slower than the reel. By coupling the spiral spring between the gear train input and gear train output, high energy density springs may be used, which may allow for decrease in housing size, increase in tape length or thickness for a given housing size, and/or advantageous retraction speed control.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This application is a continuation of International Application No.PCT/US2018/023391, filed Mar. 20, 2018, which claims priority to and thebenefit of each of U.S. Provisional Application No. 62/474,872, filedMar. 22, 2017, and U.S. Provisional Application No. 62/598,890, filedDec. 14, 2017, all of which are incorporated herein by reference intheir entireties.

BACKGROUND OF THE INVENTION

The present invention relates generally to the field of tools. Thepresent invention relates specifically to a tape measure, measuringtape, retractable rule, etc., that includes a spring-based retractionsystem having a gear train located between a tape reel and a rotatableaxle and a spiral spring coupled between the reel and the rotatableaxle.

Tape measures are measurement tools used for a variety of measurementapplications, including in the building and construction trades. Sometape measures include a graduated, marked blade wound on a reel and alsoinclude a retraction system for automatically retracting the blade ontothe reel. In some typical tape measure designs, the retraction system isdriven by a coil or spiral spring that is tensioned, storing energy asthe tape is extended, and that releases energy to spin the reel, windingthe blade back onto the reel.

SUMMARY OF THE INVENTION

One embodiment of the invention relates to a tape measure with aspring-based retraction system including a reel and a spiral spring. Thespiral spring includes an outer end coupled to the reel and an inner endthat is coupled to an axle. Both the axle and reel are rotatably mountedwithin the tape measure housing. A gear train is coupled between thereel and the axle. The gear train may be configured such that everyrotation of the reel during tape extension results in less than onerotation of the axle. The gear train may be an epicyclic gear trainhaving a central rotational axis aligned with a rotational axis of theaxle.

In some embodiments, the outer end of the spring is directly coupled toan inner surface of the reel. In some such embodiments, no additionalstructure is located radially between the outer end of the spring andthe inner surface of the reel. In some embodiments, during tapeextension and/or retraction, the outer end of the spring has an angularvelocity greater than the angular velocity of the inner end of thespring.

In some embodiments, the gear ratio of the gear train is greater than 1and less than 2. In some embodiments, the gear train defines a springturn ratio, defined as the number of reel rotations per turn applied tothe spring, and in some embodiments the spring turn ratio is 2 to 10, is3 to 6, is 3 to 4, is 4 to 5, is 5 to 6 and/or is 3.5 to 4.5.

Additional features and advantages will be set forth in the detaileddescription which follows, and, in part, will be readily apparent tothose skilled in the art from the description or recognized bypracticing the embodiments as described in the written description andclaims hereof, as well as the appended drawings. It is to be understoodthat both the foregoing general description and the following detaileddescription are exemplary.

The accompanying drawings are included to provide further understandingand are incorporated in and constitute a part of this specification. Thedrawings illustrate one or more embodiments and, together with thedescription, serve to explain principles and operation of the variousembodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a tape measure including a gearedretraction control system, according to an exemplary embodiment.

FIG. 2 is a schematic view of a gear retraction control system for atape measure, according to an exemplary embodiment.

FIG. 3 is a cross-sectional perspective view of a tape measure includinga geared retraction control system, according to an exemplaryembodiment.

FIG. 4 is a graph showing the effect of the spring turn ratio of ageared retraction control system on the preload torque of a tape measurespiral spring, according to an exemplary embodiment.

FIG. 5 is a cross-sectional perspective view of a tape measure includinga geared retraction control system, according to another exemplaryembodiment.

FIG. 6 is a cross-sectional perspective view of a tape measure includinga geared retraction control system, according to another exemplaryembodiment.

FIG. 7 is a perspective view of the geared retraction control system ofFIG. 6, according to an exemplary embodiment.

FIG. 8 is a cross-sectional perspective view of the tape measureincluding the geared retraction control system of FIG. 6, according toan exemplary embodiment.

FIG. 9 is a cross-sectional perspective view of a tape measure includinga geared retraction control system, according to another exemplaryembodiment.

FIG. 10 is a cross-sectional perspective view of a tape measureincluding a geared retraction control system, according to anotherexemplary embodiment.

FIG. 11 is a cross-sectional perspective view of a tape measureincluding a geared retraction control system, according to anotherexemplary embodiment.

FIG. 12 is a cross-sectional perspective view of a tape measureincluding a geared retraction control system, according to anotherexemplary embodiment.

FIG. 13 is a cross-sectional perspective view of a tape measureincluding a geared retraction control system, according to anotherexemplary embodiment.

FIG. 14 is a cross-sectional perspective view of a tape measureincluding a geared retraction control system, according to anotherexemplary embodiment.

FIG. 15 is a cross-sectional perspective view of a tape measureincluding a geared retraction control system, according to anotherexemplary embodiment.

FIG. 16 is a cross-sectional perspective view of a tape measureincluding a geared retraction control system, according to anotherexemplary embodiment.

FIG. 17 is a cross-sectional perspective view of a tape measureincluding a geared retraction control system, according to anotherexemplary embodiment.

FIG. 18 is a cross-sectional perspective view of a tape measureincluding a geared retraction control system, according to anotherexemplary embodiment.

FIG. 19 is a cross-sectional perspective view of a tape measureincluding a geared retraction control system, according to anotherexemplary embodiment.

FIG. 20 is an exploded perspective view of the tape measure of FIG. 19,according to an exemplary embodiment.

FIG. 21 is a perspective view of the tape spool and spool cover tapemeasure of FIG. 19, according to an exemplary embodiment.

FIG. 22 is a cross-sectional perspective view of a tape measureincluding a geared retraction control system, according to anotherexemplary embodiment.

FIG. 23 is an exploded perspective view of the tape measure of FIG. 22,according to an exemplary embodiment.

FIG. 24 is a perspective view of the axle and gear carrier of FIG. 22,according to an exemplary embodiment.

FIG. 25 is a method of manufacturing the tape measure of FIG. 22,according to an exemplary method.

DETAILED DESCRIPTION

Referring generally to the figures, various embodiments of a tapemeasure are shown. Various embodiments of the tape measure discussedherein include an innovative retraction system designed to provide for avariety of desired retraction characteristics, includingcontrolled/reduced retraction speed. Some tape measure blades aresusceptible to damage/breakage due to high speed during retraction. Forexample, high speeds during retraction may cause the tape blade to whip(e.g., the tendency of the tape measure blade to bend or snap back onitself during fast retraction), which can crack or tear the tape blade,and similarly, high retraction speeds can damage the tape blade when thetape hook contacts the tape housing at the end of retraction. Applicantbelieves that the tape measure retraction system described hereinprovides for retraction speed control that can limit such sources oftape measure damage while at the same time providing a more compact tapemeasure without sacrificing tape length or retraction performance.

As will generally be understood, in certain tape measure designs, aspring stores energy during tape blade extension and applies aforce/torque to a reel causing the tape blade to wind on to the reelduring tape blade retraction. Various aspects of spring design, such asspring energy, torque profile, spring constant, etc., are selected toensure that operation of the spring has enough energy to providesatisfactory tape retraction. However, because of the physics andcharacteristics of the typical tape measure spiral spring, in order toensure full tape retraction at a satisfactory speed, the typical tapemeasure spiral spring delivers excess energy to the tape blade duringretraction, which in turn translates into undesirably highly retractionspeeds and whip, particularly toward the end of retraction. In addition,for a given spiral spring design increasing spring energy to provide forretraction of longer, wider and/or thicker measuring tape bladestypically requires use of a larger spiral spring, which in turn resultsin a larger tape measure.

As discussed herein, Applicant has developed various innovative tapemeasure blade retraction systems that provide a desired level of springenergy while utilizing a relatively short or small volume spring, whilemaintaining a relatively small tape measure housing (e.g., a tapemeasure outer diameter) and/or while providing desired retractioncharacteristics. As discussed in more detail, the tape retraction systemdiscussed herein utilizes a gear train having its input coupled to arotating tape reel, the output coupled to a rotating central arbor oraxle, and one portion coupled to a stationary tape measure housing. Thetape retraction system also includes a spring, such as a spiral spring,coupled at its inner end to the rotating axle and at its outer end tothe rotating tape reel. In general, the gear train is a reduction geartrain that translates each rotation of the tape reel to less than onerotation of the axle, and both the tape reel and the axle rotatetogether during tape extension and retraction.

As compared to a gear reduction arrangement in which the input of a geartrain is coupled to the tape reel and the output of the gear train iscoupled to the outer end of the spiral spring, the gear trainarrangement discussed herein provides for space savings within the reel,which can be utilized to further decrease spring size, allowing housingsize to be decreased. Alternatively, the space savings provided by theretraction system arrangements discussed herein can be utilized toincrease spring energy for a fixed housing size, which allows for alonger tape blade to be deployed within a smaller tape housing thanwould typically be needed to accommodate the longer tape length. As willbe understood from the description below, the gear train operates in onedirection during tape measure extension as the reel drives winding ofthe spiral spring, and the gear train operates in the opposite directionduring tape measure retraction as the expanding spiral spring drivesrotation of the reel and tape blade uptake. As used herein, thedirectionality of the gear train (e.g., input and output) refers tooperation of the gear train during tape extension, with theunderstanding that the gear train operates in the opposite directionduring tape blade retraction.

Referring to FIGS. 1-3, a length measurement device, tape measure,measuring tape, retractable rule, etc., such as tape measure 10, isshown according to an exemplary embodiment. In general, tape measure 10includes a housing 12 having a first part 14 and a second part 16. Tapemeasure 10 includes a tape blade 18 and, in the retracted position shownin FIGS. 1 and 2, tape blade 18 is wound or coiled onto a tape reel 20.In general, tape blade 18 is an elongated strip of material including aplurality of graduated measurement markings, and in specificembodiments, tape blade 18 is an elongated strip of metal material(e.g., steel material) that includes an outer most end coupled to a hookassembly 22. Tape blade 18 may include various coatings (e.g., polymercoating layers) to help protect tape blade 18 and/or the graduatedmarkings of the blade from wear, breakage, etc.

In general, tape reel 20 is rotatably mounted within housing 12 andpositioned around an axle 24. As will be explained in more detail below,axle 24 is rotatably mounted within housing 12 such that axle 24 isallowed to rotate relative to housing 12 during tape extension orretraction.

As shown schematically in FIG. 2, tape measure 10 includes a retractionsystem 40 that includes a spring, shown as spiral spring 26. In general,spiral spring 26 is coupled between axle 24 and tape reel 20 (or throughtape reel 20 to directly couple to an inner end of tape 18) such thatspiral spring 26 is coiled or wound to store energy during extension oftape 18 from housing 12 and is unwound, releasing energy, drivingrewinding of tape 18 onto tape reel 20 during retraction of tape 18(e.g., following release or unlocking of the tape 18). Specifically,when tape blade 18 is unlocked or released, spring 26 expands, drivingtape reel 20 to wind up tape blade 18 and to pull tape blade 18 backinto housing 12.

As shown in FIG. 3, the non-extended portion of tape 18 is wound onto areel 20, which is surrounded by housing 12. Reel 20 is rotatablydisposed about an axis 28 of tape measure 10, and spring 26 is coupledto reel 20 and configured to drive reel 20 about rotation axis 28, whichin turn provides powered retraction of tape blade 18. Referring to FIG.1, a tape lock 30 is provided to selectively engage tape blade 18, whichacts to hold tape blade 18 and reel 20 in place such that an extendedsegment of tape blade 18 remains at a desired length.

A slot 32 is defined along a forward portion of housing 12. Slot 32provides an opening in the tape measure housing 12, which allows tapelock 30 to extend into housing 12 and to engage with tape 18 or reel 20.In addition, slot 32 provides a length sufficient to allow tape lock 30to be moved relative to housing 12 between locked and unlockedpositions. Below slot 32, a tape port 34 is provided in tape housing 12.In one embodiment, tape port 34 has an arcuate shape, corresponding toan arcuate cross-sectional profile of tape blade 18. Tape port 34 allowsfor the retraction and extension of tape blade 18 into and from housing12 during tape extension and retraction.

Referring to FIG. 2, a schematic view of tape measure 10 includingretraction system 40 is shown. In general, retraction system 40 includesa gear train 42. Gear train 42 includes an input 44 that is coupled totape reel 20 and an output 46 that is coupled to rotating axle 24. Inparticular embodiments, gear train 42 is a reduction gear train thatprovides gear reduction between tape reel 20 and axle 24 such that foreach rotation of tape reel 20 (e.g., during tape extension), axle 24experiences less than one rotation. In specific embodiments, the gearreduction provided by gear train 42 is at least 21 reel turns to 20 axleturns (21/20), specifically at least 11 reel turns to 10 axle turns(11/10), and more specifically at least 8 reel turns to 7 axle turns(8/7). In a specific embodiment, gear train 42 provides a gear reductionof 6 reel turns to 5 axle turns (6/5).

In specific embodiments, both reel 20 and axle 24 are rotating in thesame direction, which in turn causes the inner end of spring 26 (coupledto axle 24) and the outer end of spring 26 (coupled to reel 20) torotate in the same direction as each other. Thus, by coupling spring 26between two rotating portions of retraction system 40, the number ofturns that spring 26 experiences per rotation of reel 20 issubstantially greater than the number of rotations axle 24 experiencesper rotation of reel 20. As will be understood, while the specifics ofthe gear reduction calculation will vary based on the specific geararrangement used, the following formula defines the spring turn ratio ofthe various gear trains discussed herein:

$\begin{matrix}\begin{matrix}{{{Spring}\mspace{14mu} {Turn}\mspace{14mu} {Ratio}} = {\frac{\# \mspace{14mu} {of}\mspace{14mu} {reel}\mspace{14mu} {turns}}{\begin{matrix}{\# \mspace{14mu} {of}\mspace{14mu} {turns}} \\{{applied}\mspace{14mu} {to}\mspace{14mu} {spring}}\end{matrix}} = \frac{1}{1 - \frac{1}{{Gear}\mspace{14mu} {Ratio}}}}} \\{= \frac{1}{1 - \frac{\# \mspace{14mu} {of}\mspace{14mu} {axle}\mspace{14mu} {turns}}{\# \mspace{14mu} {of}\mspace{14mu} {reel}\mspace{14mu} {turns}}}}\end{matrix} & {{Equation}\mspace{14mu} 1}\end{matrix}$

In this manner, by providing gear reduction between tape reel 20 andaxle 24, and by locating spring 26 between the rotating input and outputof gear train 42, the number of turns spring 26 experiences for eachrotation of reel 20 can be decreased by utilizing a gear train with arelatively low gear ratio. By decreasing the number of turns of spring26 (as compared to a standard spiral spring) needed to achieve fullextension of tape blade 18 from reel 20, spring 26 can be formed fromstiffer material that is more energy dense (spring energy stored perunit volume occupied by the spring) than a spring compliant enough toexperience a high number of turns. In specific embodiments, gear train42 is configured such that the Spring Turn Ratio is greater than 1, isbetween 2 to 10, is between 3 to 6, is between 3 to 4, is between 4 to5, is between 5 to 6 or is between 3.5 to 4.5. In one specificembodiment, the Spring Turn Ratio of gear train 42 is 3.95 to 4.05, andin another specific embodiment, the Spring Turn Ratio of gear train 42is between 5.5 and 6.5, and specifically is 6. In additional specificembodiments, gear train 42 is configured such that the ratio ofrotations of reel 20 to the rotations of axle 24 is between 1 to 2, isbetween 1.1 to 1.6, is between 1.2 to 1.5 (this embodiment correlates tothe embodiment of gear train 42 with a Spring Turn Ratio between 3 to6), is between 1.3 to 1.45 or is between 1.36 to 1.42. Applicantbelieves that retraction control systems having ratios within theseranges generally provide satisfactory torque profiles and spring sizesfor tape measure applications.

Thus, retraction system 40 allows for a desired level of torque/energyto be delivered by spiral spring 26 while decreasing the total volume ofspiral spring 26 (e.g., reducing width or length of spring 26). Inspecific embodiments, by reducing the total length of spiral spring 26,the diameter of spiral spring 26 can be reduced as compared to a tapemeasure retraction system with the same torque/energy needs but does notutilize gear reduction as discussed herein. Further, by utilizingretraction system 40 with the gear train arrangements discussed herein,spring 26 is coupled at its outer end directly to reel 20, whicheliminates the need for additional transmission elements to be locatedwithin reel 20 to effect the coupling between the spring and the gearsystem. This extra volume can be used for additional spring size or foradditional tape length while maintaining a selected outer tape measurehousing.

In general as noted above, using a thicker spring increases torque whilereducing the number of turns applied to the spring to achieve aparticular level of energy stored within the spring. Thus, by utilizinga reduction gear drive, such as gear train 42, a smaller, more compactspring can be used by taking advantage of the increased power density ofthe lower turn spring. In specific embodiments, spring 26 and gear train42 are configured to deliver a preload torque of 0.5-2.5 in-lbf, andspecifically of 1.0-1.4 in-lbf, and a maximum torque reacting betweenreel 20 and axle 24 of 3-20 in-lbf, and specifically of 6.0-12.0 in-lbf.Referring to FIG. 4, the effect on preload torque of various gear ratiosis shown for an exemplary tape measure and spring having the followingcharacteristics: 0.25 mm spring thickness, 40 mm tape housing innerdiameter and 65 operating turns. As shown in FIG. 4, preload torquedecreases as spring turn ratio increases. Given a desired target preloadtorque of between 1.0-1.4 in-lbf, a spring turn ratio of between about4.5:1 to 6:1 is desirable for the given spring and tape housing shown inFIG. 4.

As will be understood, the retraction speed delivered to reel 20 isrelated to the torque and energy supplied by spring 26 and gear train 42to reel 20 during retraction. In specific embodiments, spring 26 andgear train 42 are configured to deliver a desired rotation speed to reel20 during retraction of between 200 rpm to 1500 rpm, specifically of 500rpm to 900 rpm and more specifically of between 650 rpm to 750 rpm.

Retraction system 40 also includes a fixed, rigid connection 48 couplinggear train 42 to housing 12. As will be generally understood, onecomponent of gear train 42 is coupled to housing 12 via connection 48,which allows for the rotation transfer and gear reduction from input 44to output 46 of gear train 42. As will be discussed in detail below,which gear train components are coupled to reel 20, to axle 24 and tohousing 12 through connection 48 will vary based on the particular geartrain design used. However, as noted above, in various embodiments, arotatable component of gear train 42 is coupled to reel 20 such thatrotation of reel 20 is transferred to gear train 42 and a rotatablecomponent of gear train 42 is coupled to axle 24 such that rotation ofreel 20 is transferred through gear train 42 to axle 24.

In various embodiments, gear train 42 may be any one of a variety ofepicyclic gear train designs. In specific embodiments, gear train 42 isany one of the gear arrangements shown and described in ANSI/AGMA6123-B06. In other embodiments, gear train 42 includes two or moreepicyclic gear arrangements connected to each in series in which theinput of a first epicyclic gear arrangement is coupled to reel 20, theoutput of the first epicyclic gear arrangement is coupled to the inputof a second gear arrangement, and the output of the second epicyclicgear arrangement is coupled to axle 24. This pattern can be repeated forgear trains 42 that include, 3, 4, 5, etc. epicyclic gear trains inseries. In other embodiments, gear train 42 is a gear arrangement notdescribed in ANSI/AGMA 6123-B06. As will be understood, utilizing someepicyclic gear arrangements in which the input of the gear train iscoupled to reel 20, the output is coupled to axle 24 and spring 26 iscoupled between reel 20 and axle 24, spring 26 is wound in the samedirection as rotation of reel 20 during tape extension, and in otherembodiments, spring 26 is wound in the opposite direction of rotation ofreel 20 during tape extension.

While Applicant generally understands that a wide variety of epicyclicgear train arrangement may be implemented as gear train 42 discussedabove, Applicant believes that certain gear train arrangements providefor efficient space use within tape housing 12, low complexity,desirable torque characteristics, etc. Specific exemplary embodiments ofsuch gear trains are shown in FIGS. 2 and 5-18.

Referring to FIG. 3, in a specific embodiment, gear train 42 may be aplanetary gear train 50. Planetary gear train 50 includes a central orsun gear 52, an outer ring gear 54, a gear carrier 56 and at least twoplanetary gears 58.

As shown in FIG. 3, sun gear 52 is rigidly coupled to tape housing 12and provides fixed connection 48 between planetary gear train 50 andhousing 12. Sun gear 52 defines an axis of rotation of gear train 50that is co-linear with rotation axis 28 of tape measure 10. In thespecific embodiment shown, sun gear 52 is a gear structure that extendsinward from an inner surface of tape housing 12. In one embodiment, sungear 52 is a structure that is integrally formed or molded with acomponent of housing 12, and in another embodiment, sun gear 52 is aseparate piece coupled (e.g., through an adhesive, weld, friction fit,etc.) to the inner surface of housing 12.

Outer ring gear 54 is rigidly coupled to reel 20. As shown in FIG. 3,outer ring gear 54 is formed on an annular flange 60 that extendsoutward from reel 20. As will be understood (see FIG. 5), outer ringgear 54 includes gear teeth extending radially inward from an inner,generally cylindrical surface of annular flange 60 such that outer ringgear 54 surrounds rotation axis 28. In some embodiments, outer ring gear54 and reel 20 are integrally formed or molded from a single, contiguousand continuous piece of material, and in another embodiment, outer ringgear 54 is a separate piece coupled (e.g., through an adhesive, weld,friction fit, etc.) to an outer surface of reel 20.

Planetary gears 58 are mounted to posts 62 of gear carrier 56. Gearcarrier 56 is rigidly (e.g., non-rotationally) coupled to axle 24. Thegear teeth of planetary gears 58 interface with gear teeth of outer ringgear 54 and with the gear teeth of fixed sun gear 52. In thisarrangement, as reel 20 rotates during tape extension, the interfacebetween outer ring gear 54 and planetary gears 58 translates rotationalmotion of reel 20 to planetary gears 58. Through the engagement betweenplanetary gears 58 and sun gear 52, planetary gears “orbit” around sungear 52 which, in turn translates the orbital movement of planetarygears 58 to gear carrier 56 and to axle 24. In the specific embodimentshown in FIG. 3, planetary gear train 50 results in rotation of axle 24in the same direction as reel 20, such that spiral structure of spring26 is coiled in the same direction as tape 18 on reel 20.

As will be understood, the relative sizing of sun gear 52, ring gear 54and planetary gears 58 dictates the gear reduction between reel 20 andaxle 24. Thus, this relative sizing of gear train components dictatesthe spring turn ratio (see Equation 1 above) for planetary gear train50.

Referring to FIG. 3, in addition to the increased spring energy densityand the resulting space savings within housing 12 provided by the gearreduction of planetary gear train 50, the arrangement of planetary geartrain 50 relative to spring 26 and reel 20 shown in FIG. 3 providesfurther space savings. In particular, in the embodiment of FIG. 3,spring 26 is coupled directly between reel 20 and axle 24, which allowsspring 26 to be sized to fill the entire cross-sectional diameter ofinternal chamber 64 of reel 20. Thus, in such embodiments, the outermostcoil of spring 26 faces the inner cylindrical surface of reel 20 withouta component of planetary gear train 50 located between spring 26 andreel 20. In addition, compared to some epicyclic gear arrangements,planetary gear train 50 further provides for a relatively low number ofmoving components. Also, planetary gear train 50 only results in arelatively minor addition to tape measure width as only one layer ofgearing is arranged in the width direction between housing 12 and reel20/axle 25.

Referring to FIG. 5, tape measure 10 may include a gear train, shown asgear train 70. Gear train 70 is an exemplary embodiment of gear train 42discussed above regarding FIG. 2. In this embodiment, gear train 70includes a pair of opposing planetary gear trains 50. In the embodimentshown in FIG. 5, one planetary gear train 50 is located on one side ofreel 20 and a second planetary gear train 50 is located on the otherside of reel 20. In this arrangement, spring 26 is located within reel20 and located between the two opposing planetary gear trains 50 alongaxis of rotation 28.

Referring to FIGS. 6-8, tape measure 10 may include a gear train, shownas gear train 80. Gear train 80 is an exemplary embodiment of gear train42 discussed above regarding FIG. 2. As shown, gear train 80 is anepicyclic gear train and includes an outer ring gear 82, an inner ringgear 84 and at least two planetary gears 86.

Outer ring gear 82 is rigidly coupled to reel 20. As shown in FIG. 6,outer ring gear 54 is located on annular flange 60 that extends outwardfrom reel 20. As will be understood (see FIG. 5), outer ring gear 82includes gear teeth extending radially inward from an inner, generallycylindrical surface of annular flange 60. In some embodiments, outerring gear 82 and reel 20 are integrally formed or molded from a single,contiguous and continuous piece of material, and in another embodiment,outer ring gear 82 is a separate piece coupled (e.g., through anadhesive, weld, friction fit, etc.) to an outer surface of reel 20.

Each planetary gear 86 is rotationally mounted to posts 88 that arerigidly coupled to the inner surface of housing 12. Posts 88 are rigidlycoupled to tape housing 12 such that planetary gears 86 are preventedfrom translating relative to housing 12 but are permitted to spin orrotated about posts 88 to translate rotation to axle 24. In this manner,posts 88 provide the fixed connection (see connection 48 in FIG. 2)between gear train 80 and housing 12.

Each planetary gear 86 includes an outer or high gear section 90 and aninner or low gear section 92. Inner ring gear 84 is rigidly coupled axle24 through plate 94. In some embodiments, inner ring gear 84 and/orplate 94 are integrally formed or molded from a single, contiguous andcontinuous piece of material with axle 24, and in another embodiment,inner ring gear 84 and/or plate 94 are separate pieces coupled (e.g.,through an adhesive, weld, friction fit, etc.) to axle 24.

In operation during tape extension, outer ring gear 82 engages high gearsection 90 of each planetary gear 86 such that rotation of reel 20translates into rotation of each planetary gear 86 about its post 88.Low gear section 92 of each planetary gear 86 engages inner ring gear 84such that rotation of the planetary gears 86 translates into rotation ofinner ring gear 84. Through the rigid coupling between inner ring gear84 and axle 24, the rotation of inner ring gear 84 causes rotation ofaxle 24. In the specific embodiment shown in FIGS. 6-8, gear train 80results in rotation of axle 24 in the same direction as reel 20, suchthat spiral structure spring 26 is coiled in the same direction as tape18 on reel 20.

Referring to FIG. 9, tape measure 10 may include a gear train, shown asgear train 100. Gear train 100 is an exemplary embodiment of gear train42 discussed above regarding FIG. 2. As shown, gear train 100 is anepicyclic gear train and includes a small sun gear 102, a large sun gear104 and at least two planetary gears 106.

As shown in FIG. 9, small sun gear 102 is rigidly coupled to tapehousing 12 and provides fixed connection 48 (see FIG. 2) between geartrain 100 and housing 12. In the specific embodiment shown, small sungear 102 is a gear structure that extends inward from an inner surfaceof tape housing 12. In one embodiment, small sun gear 102 is a structurethat is integrally formed or molded with a component of housing 12, andin another embodiment, sun small gear 102 is a separate piece coupled(e.g., through an adhesive, weld, friction fit, etc.) to the innersurface of housing 12.

As shown in FIG. 9, large sun gear 104 is rigidly coupled to axle 24 andhas an outer diameter greater than that of small sun gear 102. In thespecific embodiment shown, large gear 104 is a gear structure thatextends outward from one of the outer ends of axle 24 in the directionof rotation axis 28. In one embodiment, large sun gear 104 is astructure that is integrally formed or molded with the end of axle 24,and in another embodiment, large sun gear 104 is a separate piececoupled (e.g., through an adhesive, weld, friction fit, etc.) to the endof axle 24.

Gear train 100 includes at least two planetary gears 106 that aremounted to posts 108. Posts 108 extend outward in a direction parallelto rotational axis 28 from outer lateral surfaces of reel 20. In thismanner, posts 108 couple planetary gears 106 to reel 20.

Each planetary gear 106 includes an outer or high gear section 110 andan inner or low gear section 112. As shown in FIG. 9, the outer diameterof each high gear section 110 is greater than the outer diameter of lowgear section 112. The gear teeth of high gear section 110 engage withsmall sun gear 102, and the gear teeth of low gear section 112 engagewith large sun gear 104.

The coupling between reel 20 and planetary gears 106 through posts 108carries planetary gears 106 around small sun gear 102 during tapeextension. The engagement between low gear section 112 and large sungear 104 drives rotation of axle 24 as planetary gears 106 rotate ororbit around small sun gear 102. In the specific embodiment shown inFIG. 9, gear train 100 results in rotation of axle 24 in the samedirection as reel 20, such that spiral structure spring 26 is coiled inthe same direction as tape 18 on reel 20.

Referring to FIG. 10, tape measure 10 may include a gear train, shown asgear train 120. Gear train 120 is an exemplary embodiment of gear train42 discussed above regarding FIG. 2. Gear train 120 is similar to geartrain 42 shown in FIG. 3 except as discussed herein. As shown, geartrain 120 is an epicyclic gear train and includes a central or sun gear52, an outer ring gear 54, a gear carrier 56 and at least two planetarygears 122.

Each planetary gear 122 includes an outer or high gear section 124 andan inner or low gear section 126. Planetary gears 122 are mounted toposts 128 of gear carrier 56. The gear teeth of low gear section 126 ofplanetary gears 122 interface with gear teeth of outer ring gear 54. Thegear teeth of high gear section 124 of planetary gears 122 interfacewith the gear teeth of fixed sun gear 52. In this arrangement, as reel20 rotates during tape extension, the interface between outer ring gear54 and the gear teeth of low gear section 126 of planetary gears 122translates rotational motion of reel 20 to planetary gears 122. Throughthe engagement between planetary gears 122 and sun gear 52, planetarygears 122 “orbit” around sun gear 52, which in turn translates the orbitmovement to gear carrier 56 and axle 24. In the specific embodimentshown in FIG. 10, gear train 120 results in rotation of axle 24 in thesame direction as reel 20, such that spiral structure spring 26 iscoiled in the same direction as tape 18 on reel 20.

FIGS. 11-18 show tape measure 10 including various epicyclic gear trainarrangements according to additional exemplary embodiments. In generalthe gear train arrangements shown in FIGS. 11-18 are similar to thosediscussed above, in that they provide gear reduction between the reeland the axle such that the number of turns applied to the spring perreel revolution is decreased.

Referring to FIG. 11, gear carrier 56 is coupled to housing 12 andincludes posts 62, around which inner planetary gear 92 and outerplanetary gear 90 are rotatably mounted. The gear teeth of outerplanetary gear 90 interface with outer ring gear 82 and inner planetarygear 92, the gear teeth of which also interface with inner ring gear 84.Outer ring gear 82 is coupled to axle 24, inner ring gear 84 is coupledtape reel 20, and spring 26 is coupled between tape reel 20 and axle 24.

Referring to FIG. 12, gear carrier 56 is coupled to tape reel 20 andincludes posts 62, around which inner planetary gear 92 and outerplanetary gear 90 are rotatably mounted. The gear teeth of outerplanetary gear 90 interface with outer ring gear 54 and inner planetarygear 92, the gear teeth of which also interface with sun gear 52. Sungear 52 is coupled to housing 12, outer ring gear 54 is coupled to axle24, and spring 26 is coupled between tape reel 20 and axle 24.

Referring to FIG. 13, gear carrier 56 is coupled to axle 24 and includesposts 62, around which inner planetary gear 92 and outer planetary gear90 are rotatably mounted. The gear teeth of outer planetary gear 90interface with outer ring gear 54 and inner planetary gear 92, the gearteeth of which also interface with sun gear 52. Outer ring gear 54 iscoupled to tape reel 20, sun gear 52 is coupled to housing 12, andspring 26 is coupled between tape reel 20 and axle 24.

Referring to FIG. 14, gear carrier 56 is coupled to axle 24 and includesposts 62, around which inner planetary gear 92 and outer planetary gear90 are rotatably mounted. The gear teeth of outer planetary gear 90interface with outer ring gear 54 and inner planetary gear 92, the gearteeth of which also interface with sun gear 52. Outer ring gear 54 iscoupled to tape reel 20, sun gear 52 is coupled to housing 12, andspring 26 is coupled between tape reel 20 and axle 24.

Referring to FIG. 15, gear carrier 56 is coupled to axle 24 and includesposts 62, around which inner planetary gear 92 and outer planetary gear90 are rotatably mounted. The gear teeth of outer planetary gear 90interface with outer ring gear 82 and inner planetary gear 92, the gearteeth of which also interface with inner ring gear 84. Outer ring gear82 is coupled to tape reel 20, inner ring gear 84 is coupled to housing12, and spring 26 is coupled between tape reel 20 and axle 24.

Referring to FIG. 16, gear carrier 56 is coupled to axle 24. Tape reel20 includes posts 62, around planetary gear 58 is rotatably mounted. Thegear teeth of inner planetary gear 92 interface with outer ring gear 82,and the gear teeth of outer planetary gear 90 interface with inner ringgear 84. Outer gear ring 82 is coupled to housing 12, inner gear ring 84is coupled to gear carrier 56, and spring 26 is coupled between tapereel 20 and axle 24.

Referring to FIG. 17, gear carrier 56 is coupled to axle 24. Posts 62are coupled to tape reel 20, and planetary gears 58 are rotatablymounted to posts 62. The gear teeth of outer planetary gear 90 interfacewith outer ring gear 82, and the gear teeth of inner planetary gear 92interface with inner ring gear 84. Outer gear ring 82 is coupled tohousing 12, inner gear ring 84 is coupled to gear carrier 56, and spring26 is coupled between tape reel 20 and axle 24.

Referring to FIG. 18, gear carrier 56 is coupled to axle 24 and includesposts 62, around which inner planetary gear 92 and outer planetary gear90 are rotatably mounted. The gear teeth of outer planetary gear 90interface with inner ring gear 84 and inner planetary gear 92, the gearteeth of which also interface with outer ring gear 82. Inner gear ring84 is coupled to tape reel 20, outer ring gear 82 is coupled to housing12, and spring 26 is coupled between tape reel 20 and axle 24.

Referring now to FIG. 19, in various embodiments, tape measure 10 mayinclude one or more structures configured to reduce friction while tapereel or spool 20 is rotating (e.g., while housing 12 is paying out orretrieving tape blade 18). On the left side of spool 20 in FIG. 19,spool 20 is supported radially by axle or carrier 24 at contact surface150. On the right side of spool 20 in FIG. 19, spool 20 is indirectlysupported radially by carrier 24 via spool cover 132 at contact surface150. On both sides of carrier 24, carrier 24 itself is confined byhousing 12 at contact surface 150.

In one embodiment, carrier 24 has a diameter of 5 mm and is created fromdiecast Zinc, although it is contemplated herein that other diameters,manufacturing methods and/or materials may be utilized and stillpractice the disclosure herein.

Contact surfaces 150, which include the bearing interfacing surfaces ofspool 20 and spool cover 132, are located directly around carrier 24.The area of contact surfaces 150 is reduced because the diameter of thebearing surface is smaller relative to other embodiments in which thebearing surface is located at an increased diameter from carrier 24. Asa result, the amount of energy lost to friction while spool 20 rotatesis concurrently reduced. Therefore less torque is required to providefull retraction of spool 20 and of the tape blade.

Tape measure 10 includes dust cover 130, which at least partiallyencloses the interface between planetary gears 58 and both sun gear 52and outer ring gear 54 (best shown in FIG. 20).

In the embodiment in FIG. 19, similar to one or more other embodimentsdescribed herein, spring 26 is anchored to carrier 24 and spool 20, andplanetary gears 58 interface with and rotate around sun gear 52 (bestshown in FIG. 20). The outer periphery of planetary gears 58 alsointerface with outer ring gear 54. Both spool 20 (also referred to astape reel 20) and carrier 24 (also referred to as axle 24) rotate aboutthe longitudinal axis of axle 24 relative to and within housing 12.

Referring now to FIG. 21, tape measure 10 also may include spool cover132, which is located on the opposite side of spool 20 relative to dustcover 130. Spool cover 132 at least partially encloses internal chamber64 of spool 20 where spring 26 is disposed. Spool cover 132 is rotatablyfixed to spool 20 and rotates about carrier 24. The tabs in spool cover132 allow for easy rotational locking with spool 20 during assembly.Support ring 134 furthers a more secure coupling between spool cover 132and spool 20, thus reducing a chance of decoupling if tape measure 10 isdropped. In an alternative embodiment spool cover 132 is not fixed tospool 20, and instead is permitted to rotate independently with respectto both carrier 24 and spool 20.

Referring now to FIG. 22, illustrated therein is another embodiment oftape measure 10. In this embodiment, tape measure 10 is designed tocreate a direct load path between the primary mass of tape measure 10(typically tape blade 18 and spring 26) into housing 12 which improvesdurability and stability, for example during impact if tape measure 10is dropped. Another aspect and advantage of this embodiment is thatinput torque is converted to higher turns at a lower torque, which isreacted at sun gear 52/front housing 12, causing tape reel 20 to rotate.

In the embodiment shown in FIG. 22, spring 26 is anchored to carrier 24and spool 20. Carrier 24 spins freely with respect to housing 12 andspool 20. Further, when tape blade 18 is being either paid out orretrieved into housing 12, carrier 24 spins in the same direction asspool 20, but at a slightly slower speed than spool 20.

In this embodiment, spool 20 is radially supported by housing 12 on theright side of FIG. 22 at contact surface 150, and by hubcap 140 on theleft side of FIG. 22 at contact surface 150. Contact surfaces 150, whichinclude the bearing interfacing surfaces of spool 20 and hubcap 140, arelocated around housing 12 as indicated in FIG. 22. Therefore, the areaof contact surfaces 150 is slightly increased relative to FIG. 19because the diameters of the bearing surfaces in FIG. 22 are relativelylarger.

Hubcap 140 partially encloses the interface between planetary gears 58and outer ring gear 54. Hubcap 140 is rotatably fixed to spool 20 (e.g.,via rivets, screws, and/or fasteners). In the embodiment illustrated inFIG. 22, hubcap 140 extends from annular flange 60 to approximate aradially interior edge of planetary gears 58. In this configurationhubcap 140 helps prevent contamination from entering the gear assembly.However, it is contemplated herein that hubcap 140 may have otherconfigurations.

Also included in the embodiment in FIG. 22 is membrane 142. Membrane 142separates internal chamber 64 from the gears, including sun gear 52,planetary gears 58, and outer ring gear 54 (best shown in FIGS. 22 and23). In one embodiment, outer ring gear 54 is configured to be disposedwithin an opening in spool 20 (best shown in FIG. 23), such that outerring gear 54 and spool 20 are rotatably fixed together.

Referring now to FIG. 24, illustrated therein is an exemplary embodimentof carrier 24. In this embodiment, carrier 24 includes gear carrier 56,which extends radially from the primary axis of carrier 24. Protrudingfrom gear carrier 56 are several posts 62, upon which planetary gears 58are disposed, and around which planetary gears 58 axially rotate. In theembodiment illustrated in FIG. 24, carrier 24 includes five posts 62,although it is contemplated herein that any number of posts may beutilized, such as for exemplary purposes only and without limitation,3-6 posts. Further, in one or more embodiments, such as FIG. 24, posts62 are symmetrically located on gear carrier 56 with respect to eachother. It should be understood that while carrier 56 is shown ascircular, in other embodiments carrier 56 may be any other suitableshape such as hexagonally shaped, D-shaped, oval shaped, an X-sidedpolygon, etc.

In one embodiment, carrier 24 has a diameter of 4.63 mm and is createdfrom diecast Zinc, although it is contemplated herein that otherdiameters, manufacturing methods and/or materials may be utilized andstill practice one or more disclosures herein.

Referring now to FIG. 25, a method of assembly of an epicyclic gearedtape measure, such as tape measure 10, is shown. At step 1, one side ofmembrane 142 is slightly lubricated, such as with grease. Membrane 142is installed onto carrier 24 with the greased side of membrane 142facing carrier 24. Spring 26 is formed around the axle of carrier 24 atstep 2, and then wound. An external tail of spring 26 is captured, spool20 is placed around spring 26 at step 3, and the external tail of spring26 is anchored to spool 20.

Planetary gears 58 are lightly lubricated (e.g., with grease) betweenplanetary gears 58 and posts 62, and then planetary gears 58 are placedon posts 62 at step 4. Outer ring gear 54 is placed around planetarygears 58 and the teeth of planetary gears 58 are lightly lubricated atstep 5. At step 6, hubcap 140 is then placed over the gear assembly andfixedly attached to spool 20 (e.g., via screws). Then, at step 7 thespool assembly is placed into housing 12 (e.g., front housing) thatincludes sun gear 52, such that planetary gears 58 are interfaced withsun gear 52. Subsequently, at step 8 the rest of tape measure 10 isassembled, such as attaching a rear housing, a bumper, a brake, and/orhousing screws to attach the housings.

The relative rotational speed of arbor 24 to spool 20 is partly based onwhether tape blade 18 and spring 26 are wound in the same direction. Todemonstrate a result of winding blade 18 and spring 26 in differentdirections, two embodiments are described below. In both embodiments,spring 26 is anchored to spool 20 on one end and to arbor 24 on theother end. In use, spool 20 and arbor 24 rotate in the same direction aseach other when tape blade 18 is being either extracted or retracted.Spool 20 and arbor 24 are both coupled to housing 12 through gear train42. Tape blade 18 is wound around spool 20, and when tape blade 18 isextended from housing 12, energy is stored in spring 26 through therotations of arbor 24 and spool 20.

In a first embodiment, spring 26 and tape blade 18 are wound in the samedirection and as a result spool 20 rotates faster than arbor 24. Forexample, if a 4:1 spring turn ratio is used with this embodiment thenspool 20 rotates 4 times while arbor 24 rotates 3 times, and the resultis one turn of force is applied to spring 26 (instead of 4 turns as in atypical tape measure in which housing 12, spring 26, spool 20, and arbor24 are in series).

In a second embodiment, case spring 26 and tape blade 18 are wound inopposite directions and as a result, arbor 24 rotates faster than spool20. For comparison, if a 4:1 spring turn ratio is used with thisembodiment then spool 20 rotates 4 times while arbor 24 rotates 5 times,and the result is one turn applied to the spring (instead of 4 turns asin a typical tape measure).

It should be understood that the figures illustrate the exemplaryembodiments in detail, and it should be understood that the presentapplication is not limited to the details or methodology set forth inthe description or illustrated in the figures. It should also beunderstood that the terminology is for description purposes only andshould not be regarded as limiting.

Further modifications and alternative embodiments of various aspects ofthe invention will be apparent to those skilled in the art in view ofthis description. Accordingly, this description is to be construed asillustrative only. The construction and arrangements, shown in thevarious exemplary embodiments, are illustrative only. Although only afew embodiments have been described in detail in this disclosure, manymodifications are possible (e.g., variations in sizes, dimensions,structures, shapes and proportions of the various elements, values ofparameters, mounting arrangements, use of materials, colors,orientations, etc.) without materially departing from the novelteachings and advantages of the subject matter described herein. Someelements shown as integrally formed may be constructed of multiple partsor elements, the position of elements may be reversed or otherwisevaried, and the nature or number of discrete elements or positions maybe altered or varied. The order or sequence of any process, logicalalgorithm, or method steps may be varied or re-sequenced according toalternative embodiments. Other substitutions, modifications, changes andomissions may also be made in the design, operating conditions andarrangement of the various exemplary embodiments without departing fromthe scope of the present invention.

Unless otherwise expressly stated, it is in no way intended that anymethod set forth herein be construed as requiring that its steps beperformed in a specific order. Accordingly, where a method claim doesnot actually recite an order to be followed by its steps or it is nototherwise specifically stated in the claims or descriptions that thesteps are to be limited to a specific order, it is in no way intendedthat any particular order be inferred. In addition, as used herein, thearticle “a” is intended to include one or more component or element, andis not intended to be construed as meaning only one. As used herein,“rigidly coupled” refers to two components being coupled in a mannersuch that the components move together in a fixed positionalrelationship when acted upon by a force.

Various embodiments of the invention relate to any combination of any ofthe features, and any such combination of features may be claimed inthis or future applications. Any of the features, elements or componentsof any of the exemplary embodiments discussed above may be utilizedalone or in combination with any of the features, elements or componentsof any of the other embodiments discussed above.

What is claimed is:
 1. A tape measure comprising: a housing; an axlerotatably mounted within the housing; a tape reel rotatably mountedwithin the housing around the axle, the tape reel comprising a radiallyinward-facing surface defining an interior reel cavity and a radiallyoutward-facing surface; an elongate tape blade wound around the radiallyoutward-facing surface of the tape reel; a hook assembly coupled to anouter end of the elongate tape blade; a spiral spring located at leastpartially within the interior reel cavity and at least partiallysurrounded by the elongate tape blade in the radial direction, thespiral spring is coupled between the tape reel and the axle such thatwhen the elongate tape blade is unwound from the tape reel to extendfrom the housing the spiral spring stores energy, and the spiral springreleasing energy drives rewinding of the elongate tape blade on to thetape reel; and a gear train rotatably coupling the tape reel and theaxle such that during extension of the elongate tape blade from thehousing, each full rotation of the tape reel results in less than a fullrotation of the axle; wherein, during extension and rewinding of theelongate tape blade, both the axle and tape reel rotate within thehousing.
 2. The tape measure of claim 1, wherein a first gear of thegear train is coupled to the housing, the elongate tape blade having anupper surface with a concave profile when extended from the housing. 3.The tape measure of claim 2, wherein a second gear of the gear train isfixedly coupled to the housing such that the second gear does not rotaterelative to the housing.
 4. The tape measure of claim 2, wherein asecond gear of the gear train is rotatably coupled to the housing, suchthat the second gear rotates relative to the housing.
 5. The tapemeasure of claim 1, wherein the axle comprises a gear carrier thatextends radially outward from an end of the axle, the gear carriercomprises a plurality of posts extending along an axis parallel to aprimary axis of the axle, and the gear train comprises: a sun gearfixedly coupled to the housing; an outer ring gear fixedly coupled tothe tape reel; and a plurality of planetary gears rotatably mounted tothe plurality of posts, the plurality of planetary gears rotatablyengaging with the outer ring gear and the sun gear.
 6. The tape measureof claim 1, wherein the axle comprises a gear carrier that extendsradially outward from an end of the axle, and the gear train comprises:a first outer ring gear fixedly coupled to the tape reel; a second outerring gear fixedly coupled to the gear carrier; a plurality of postsfixedly coupled to the housing; and a plurality of planetary gearsrotatably mounted to the plurality of posts, the plurality of planetarygears each comprising a low planetary gear and a high planetary gearthat are axially aligned, fixedly coupled to each other, and havedifferent radii than each other, wherein the low planetary gearrotatably engages with the second outer ring gear and the high planetarygear rotatably engages with the first outer ring gear.
 7. The tapemeasure of claim 6, wherein each low planetary gear has a first radiusand each high planetary gear has a second radius, the first radius beingless than the second radius.
 8. The tape measure of claim 1, the geartrain comprising: a large sun gear fixedly coupled to the axle; a smallsun gear fixedly coupled to the housing, the small sun gear having aradius that is less than a radius of the large sun gear; a plurality ofposts fixedly coupled to the tape reel, each of the plurality of postsextending along an axis parallel a primary axis of the axle; and aplurality of planetary gears rotatably mounted to the plurality ofposts, the plurality of planetary gears each comprising a high planetarygear and a low planetary gear that are fixedly coupled together, thehigh planetary gear rotatably engaging with the small sun gear and thelow planetary gear rotatably engaging with the large sun gear.
 9. Thetape measure of claim 1, wherein the tape reel comprises a radiallyinward-facing surface that engages a radially outward-facing of theaxle.
 10. The tape measure of claim 9, wherein the tape reel comprisesan internal wall that partially defines the interior reel cavity of thetape reel, that extends perpendicularly to a primary axis of the axle,and that comprises the radially inward-facing surface.
 11. The tapemeasure of claim 10, wherein the tape measure comprises a spool coverthat partially defines the interior reel cavity opposite the internalwall, and the spool cover comprises a second radially inward-facingsurface that engages with a second radially outward-facing surface ofthe axle.
 12. The tape measure of claim 1, wherein during extension ofthe elongate tape blade from the housing, a ratio of tape reel rotationsto axle rotations is greater than one and less than two.
 13. The tapemeasure of claim 1, wherein during extension of the elongate tape bladefrom the housing, a ratio of tape reel rotations to axle rotations isgreater than 1.2 and less than 1.5.
 14. A tape measure comprising: ahousing; an axle rotatably mounted within the housing; a tape reelrotatably mounted within the housing around the axle, the tape reelcomprising a radially inward-facing surface defining an interior reelcavity and a radially outward-facing surface; an elongate tape bladewound around the radially outward-facing surface of the tape reel; ahook assembly coupled to an outer end of the elongate tape blade; aspiral spring located at least partially within the interior reel cavityand at least partially surrounded by the elongate tape blade in theradial direction, the spiral spring is coupled between the tape reel andthe axle such that when the elongate tape blade is unwound from the tapereel to extend from the housing the spiral spring stores energy, and thespiral spring releasing energy drives rewinding of the elongate tapeblade on to the tape reel; and a gear train rotatably coupling the tapereel and the axle such that during extension of the elongate tape bladefrom the housing, the axle and the tape reel rotate in the samerotational direction.
 15. The tape measure of claim 14, wherein a firstgear of the gear train is coupled to the housing, the elongate tapeblade having an upper surface with a concave profile when extended fromthe housing.
 16. The tape measure of claim 14, wherein a first gear ofthe gear train is rotatably coupled to the housing, the elongate tapeblade having an upper surface with a concave profile when extended fromthe housing.
 17. The tape measure of claim 14, wherein the axlecomprises a gear carrier that extends radially outward from an end ofthe axle, the gear carrier comprises a plurality of posts extendingalong an axis parallel to a primary axis of the axle, and the gear traincomprises: a sun gear fixedly coupled to the housing; an outer ring gearfixedly coupled to the tape reel; and a plurality of planetary gearsrotatably mounted to the plurality of posts, the plurality of planetarygears rotatably engaging with the outer ring gear and the sun gear. 18.The tape measure of claim 14, wherein the axle comprises a gear carrierthat extends radially outward from an end of the axle, and the geartrain comprises: a first outer ring gear fixedly coupled to the tapereel; a second outer ring gear fixedly coupled to the gear carrier; aplurality of posts fixedly coupled to the housing; and a plurality ofplanetary gears rotatably mounted to the plurality of posts, theplurality of planetary gears each comprising a low planetary gear and ahigh planetary gear that are axially aligned, fixedly coupled to eachother, and have different radii than each other, wherein the lowplanetary gear rotatably engages with the second outer ring gear and thehigh planetary gear rotatably engages with the first outer ring gear.19. The tape measure of claim 18, wherein each low planetary gear has afirst radius and each high planetary gear has a second radius, the firstradius being less than the second radius.
 20. The tape measure of claim14, wherein the gear train comprises: a large sun gear fixedly coupledto the axle; a small sun gear fixedly coupled to the housing, the smallsun gear having a radius that is less than a radius of the large sungear; a plurality of posts fixedly coupled to the tape reel, each of theplurality of posts extending along an axis parallel a primary axis ofthe axle; and a plurality of planetary gears rotatably mounted to theplurality of posts, the plurality of planetary gears each comprising ahigh planetary gear and a low planetary gear that are fixedly coupledtogether, the high planetary gear rotatably engaging with the small sungear and the low planetary gear rotatably engaging with the large sungear.
 21. The tape measure of claim 14, wherein the tape reel comprisesan internal wall that partially defines the interior reel cavity of thetape reel, that extends perpendicularly to a primary axis of the axle,and that comprises the radially inward-facing surface.
 22. The tapemeasure of claim 21, wherein the tape measure comprises a spool coverthat partially defines the interior reel cavity opposite the internalwall, the spool cover comprises a second radially inward-facing surfacethat engages with a second outward-facing surface of the axle.
 23. Atape measure comprising: a housing; an axle rotatably mounted within thehousing; a tape reel rotatably mounted within the housing around theaxle, the tape reel comprising a radially inward-facing surface definingan interior reel cavity and a radially outward-facing surface; anelongate tape blade wound around the radially outward-facing surface ofthe tape reel, the elongate tape blade having an upper surface with aconcave profile when extended from the housing; a hook assembly coupledto an outer end of the elongate tape blade; a spiral spring located atleast partially within the interior reel cavity and at least partiallysurrounded by the elongate tape blade in the radial direction, thespiral spring is coupled between the tape reel and the axle such thatwhen the elongate tape blade is unwound from the tape reel to extendfrom the housing the spiral spring stores energy, and the spiral springreleasing energy drives rewinding of the elongate tape blade on to thetape reel; and a gear train rotatably coupling the tape reel and theaxle such that during extension of the elongate tape blade from thehousing, each full rotation of the tape reel results in less than a fullrotation of the axle; wherein, during extension and rewinding of theelongate tape blade, the axle and tape reel rotate within the housing atdifferent rotational speeds from each other.
 24. The tape measure ofclaim 23, wherein a first gear of the gear train is coupled to thehousing.
 25. The tape measure of claim 23, wherein a first gear of thegear train is rotatably coupled to the housing.
 26. The tape measure ofclaim 23, wherein the axle comprises a gear carrier that extendsradially outward from an end of the axle, the gear carrier comprises aplurality of posts extending along an axis parallel to a primary axis ofthe axle, and the gear train comprises: a sun gear fixedly coupled tothe housing; an outer ring gear fixedly coupled to the tape reel; and aplurality of planetary gears rotatably mounted to the plurality ofposts, the plurality of planetary gears rotatably engaging with theouter ring gear and the sun gear.
 27. The tape measure of claim 23,wherein the axle comprises a gear carrier that extends radially outwardfrom an end of the axle, and the gear train comprises: a first outerring gear fixedly coupled to the tape reel; a second outer ring gearfixedly coupled to the gear carrier; a plurality of posts fixedlycoupled to the housing; and a plurality of planetary gears rotatablymounted to the plurality of posts, the plurality of planetary gears eachcomprising a low planetary gear and a high planetary gear that areaxially aligned, fixedly coupled to each other, and have different radiithan each other, wherein the low planetary gear rotatably engages withthe second outer ring gear and the high planetary gear rotatably engageswith the first outer ring gear, wherein each low planetary gear has afirst radius and each high planetary gear has a second radius, the firstradius being less than the second radius.
 28. The tape measure of claim23, wherein the gear train comprises: a large sun gear fixedly coupledto the axle; a small sun gear fixedly coupled to the housing, the smallsun gear having a radius that is less than a radius of the large sungear; a plurality of posts fixedly coupled to the tape reel, each of theplurality of posts extending along an axis parallel a primary axis ofthe axle; and a plurality of planetary gears rotatably mounted to theplurality of posts, the plurality of planetary gears each comprising ahigh planetary gear and a low planetary gear that are fixedly coupledtogether, the high planetary gear rotatably engaging with the small sungear and the low planetary gear rotatably engaging with the large sungear.